People with depression are less likely to have certain gut bacteria

People who lack certain gut bacteria are more likely to experience depression, according to the largest study yet to find a link between our microbiota and mental health.

Jeroen Raes of KU Leuven University in Belgium and colleagues examined over 1000 volunteers in Belgium who’d had the bacteria living in their gut genetically sequenced as part of a larger study.

The team found that two kinds of bacteria, Dialister and Coprococcus, were less common in people who reported that they were depressed. The same result was seen in a second group of over 1000 volunteers from the Netherlands.

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This doesn’t necessarily mean that lacking these bacteria causes depression. It could be that people who have depression eat differently, for instance, and that this changes their gut flora. “To determine causality, we would need to procure these bugs and give them to mice with a version of depression,” says Raes.

But if the bacteria do play a role in preventing depression, it could be because both these microbes make an anti-inflammatory compound called butyrate, says Raes. A growing body of research has suggested the mood disorder could be caused, at least in some people, by ongoing systemic inflammation.